WO1997008811A2 - Convertisseur cc-cc a modulateur fsk integre - Google Patents

Convertisseur cc-cc a modulateur fsk integre Download PDF

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Publication number
WO1997008811A2
WO1997008811A2 PCT/EP1996/003646 EP9603646W WO9708811A2 WO 1997008811 A2 WO1997008811 A2 WO 1997008811A2 EP 9603646 W EP9603646 W EP 9603646W WO 9708811 A2 WO9708811 A2 WO 9708811A2
Authority
WO
WIPO (PCT)
Prior art keywords
converter
frequency
data
transponder
quartz
Prior art date
Application number
PCT/EP1996/003646
Other languages
German (de)
English (en)
Other versions
WO1997008811A3 (fr
Inventor
Roland Küng
Heinrich Zweifel
Original Assignee
Tagix Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tagix Ag filed Critical Tagix Ag
Priority to AU68744/96A priority Critical patent/AU6874496A/en
Publication of WO1997008811A2 publication Critical patent/WO1997008811A2/fr
Publication of WO1997008811A3 publication Critical patent/WO1997008811A3/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/0723—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Definitions

  • the present invention relates to the use of direct voltage converters (DC-DC converters) in passive transponders and electronic brands (so-called tags).
  • DC-DC converters direct voltage converters
  • DC-DC converters use a frequency signal which is not regulated in frequency to convert the DC voltage from one potential to another. If such transducers are used in passive transponders, this switching frequency can severely disrupt the transmission of data between the transponder and the reading device.
  • a frequency-modulated carrier oscillation is used, which is superimposed in a suitable form in the rectifier at a low level on the received energy carrier of the reading device.
  • the switching frequency is also disturbingly superimposed on the energy source and is thus emitted together with the carrier oscillation by the antenna.
  • passive means that there is no separate power supply on the transponder or tag and the energy for its operation must be transmitted via magnetic or electromagnetic fields.
  • transponders or tags are increasingly used, for example, for identification tags (badges), for access control (parking garage), for fee collection (highway, garbage disposal), and for telemetry (monitoring in concrete structures).
  • passive transponders or tags are known. In their most common form of use, they have a non-volatile memory and are able to receive data from a reading station 30 and also to send data to the reading station themselves (so-called read / write tag) as shown in FIG. 3 .
  • read / write tag Common to almost all methods is that it is magnetic or electromagnetic radiated high-frequency alternating signal (AC) received by an antenna and formed into a DC voltage in a rectifier (DC), and thus supplies the transponder 40 or the tag with energy.
  • AC magnetic or electromagnetic radiated high-frequency alternating signal
  • a device for sending data to the reading device, which induces a second alternating voltage of low amplitude at the rectifier, so that this alternating voltage can be emitted again by the antenna.
  • This small voltage can be achieved by changing the load on the rectifier.
  • the current in the rectifier which changes in amplitude or frequency, leads to a slight change in voltage at the antenna, which leads to retroreflection of a small part of the incident energy. Since the second alternating signal is modulated with data from the transponder or tag, the reader can thus receive and demodulate this data.
  • 3 schematically shows a passive day.
  • a DC-DC converter provides simple remedy here by chopping and rectifying the rectified DC voltage back into a defined DC voltage.
  • the control is mostly implemented by means of pulse width modulation (PWM).
  • PWM pulse width modulation
  • Such DC-DC converters with a high degree of efficiency have been known for a long time and are also used above all in battery-operated devices in order to be able to better utilize the battery to the end without passing on the voltage drop in the battery to the electronics.
  • Fig. 4 shows a block diagram of such a DC-DC converter.
  • an interference signal occurs, namely the alternating signal from the chopper.
  • the frequency of this interference signal is unregulated and is determined by a simple RC oscillator.
  • the frequency changes (typical range: 1 kHz to 50 KHz), which then falls within the frequency range provided for communication (typical range: 10 kHz to 20 kHz) and thereby can deceive or disturb the reader. 2 shows the spectrum that typically occurs with passive tags.
  • the object of the present invention is to provide a device and a method for DC-DC conversion in passive transponders, so that interference-free data transmission is made possible. This object is achieved with the features of the claims.
  • the invention is based on the basic idea of using the same frequency for DC-DC conversion in the passive transponder as for data transmission from the transponder.
  • the DC-DC converter for DC-DC conversion uses the same frequency as that used for data transmission from the transponder, the interference is completely eliminated.
  • the frequency-modulating transmitter part on the transponder is also omitted, since it is already implemented by the DC-DC converter.
  • Such a DC-DC converter with an integrated FSK modulator is particularly advantageous in the case of passive transponders or tag systems.
  • Another possible solution to the interference problem would be to filter the interference frequency towards the antenna of the transponder so that this frequency is not radiated. Since relatively large inductances and capacities are required for screening, but the passive transponders or tags are often very limited in terms of space and height, this solution is not an option.
  • the FSK modulator would have to be routed around this screening.
  • the useful and interference frequencies can only be arranged with poor spectral spacing, since this would greatly increase the power consumption of the passive part as a result of the increased clock rate.
  • FIG. 1 shows a DC-DC converter according to the invention with an FSK modulator
  • Fig. 3 is a passive transponder or tag system
  • Fig. 4 shows a known DC-DC converter.
  • the multivibrator 1 generates a square-wave signal controlled by an RC element, consisting of positive pulses of length T1 and short pauses of length T2. If the output voltage V Q TJJ is too low, the operational circuit 3 passes the square wave pulse generated by the multivibrator 1 through the logic circuit 2. This pulse switches through the MOS transistor 4 and the inductance 5 is thus charged. The charging voltage is V IN and the maximum charging current T1 * V IN / L1. After the elapsed pulse time Tl, the transistor 4 blocks and the voltage V L changes from 0 volts to a positive voltage, so that a current flows briefly via the diode 6 to the output capacitance 7.
  • V L is greater than V QUT , the operational amplifier 8 changes from the upper saturation voltage to the lower saturation voltage voltage and thereby controls the transistor 9 through.
  • the main current from the inductance now flows via the transistor 9, which has become low-resistance, into the output capacitance 7 and charges it very quickly, the inductance 5 is discharged.
  • a charging current flows until V L is equal to V 0TjT , this happening before T2 expires.
  • the following pulse again controls the transistor 4 and thus allows the output of the operational amplifier 8 to go back to positive saturation, so that the transistor 9 is switched off and the inductance can be recharged. This is repeated until the output voltage has reached the desired voltage value.
  • the integrator 10 periodically integrates the output voltage of the converter for each clock interval and the operational amplifier 3 compares the integration result with the desired reference voltage.
  • the output of the operational amplifier 3 goes into the lower saturation when V Qut reaches the desired value.
  • the pulse of the multivibrator 1 is thus interrupted prematurely in the logic circuit 2. Since this is connected as a control loop, the pulse width at the gate terminal of transistor 4 is leveled to the value which just brings a sufficient amount of charge to inductor 5 in order to renew the amount of consumption of load 11.
  • the integrator 10 requires a minimum time to reach the reference voltage, so that the pulse at the gate connection of the transistor 4 can never fall below a minimum value.
  • the start-up circuit 15 guarantees that the converter starts up properly, in that the transistor 4 remains blocked until the circuit receives enough voltage for the function to be performed correctly.
  • the multivibrator 1 is constructed as an RC oscillator.
  • the frequencies set by appropriate selection of the time constant RC become very imprecise.
  • the oscillator frequency can only be a few kHz in order to then increase to a nominal voltage of a few 10 kHz. climb. Temperature changes and specimen scatter also result in fluctuations by a significant factor.
  • the control signal at the gate connection of the transistor 4 is, as it were, radiated back as an interference signal via rectifier from the antenna due to the pulsed current draw of the inductor 5.
  • the multivibrator 1 is replaced by a quartz oscillator 12 for generating the converter frequency
  • the frequency of the DC-DC converter is stable, non-aging, temperature-independent and thus the interference is known spectrally.
  • the desired duty cycle can be set, for example, by a monoflop stage integrated in the quartz oscillator.
  • the converter frequency can be switched from N to M during operation by means of a multiplexer 14.
  • the pulse duty factor T2 / T1 can be easily set to 1: N or 1: M, for example, by logical connection with the quartz oscillator clock. If a digital data signal from a microcontroller is used for the switchover, an FSK modulator is obtained in this way, and the interference signals now appear as actual useful signals which can be used for communication from the transponder to the reading device. Since the PWM converter is constructed in such a way that the charging current in the inductance flows at least briefly in each clock period, the modulation is never interrupted, but only weakened in its amplitude.
  • FIG. 3 shows a block diagram of the DC-DC converter according to the invention with an integrated FSK modulator.
  • the microcontroller can only be used when the stabilized voltage is available.
  • the current consumption in the transition is often not defined.
  • the DC-DC converter must first work correctly.
  • the maximum current draw from the electrical or electromagnetic field is very limited, in contrast to applications with batteries as an energy source.
  • Low-power crystal oscillators can show start-up problems at low voltages and limited current consumption. If the load draws too much current when starting, the output voltage will never rise to such an extent that the oscillator or the load can work correctly. The result would be an oscillation-like oscillation between operation and non-operation.
  • an orderly switch-on procedure helps.
  • the already known RC multivibrators are generally more suitable for the first stage of switching on.
  • an RC multivibrator is now used in a conventional manner for starting, that is until a minimum output voltage is stabilized for the first time. If there is sufficient voltage at the output of the DC-DC converter is sufficient to operate the quartz oscillator, it is switched to one of the two FSK frequencies divided by the quartz oscillator for operating the DC-DC converter. When the final voltage for operating the transponder has been reached, the load, usually the microcontroller and the data receiver, is switched on. If the tag is to acknowledge information or send data to the reader, the data rate is used to switch between the two divider outputs 13 depending on the data value of the multiplexer 15.
  • the DC-DC converter operates from an input voltage of 1 V. If an output voltage of 1.5 V is reached, a voltage detector connected to the output of the DC-DC converter is already working correctly and the quartz oscillator can be switched on become. With a 3 V output voltage, the microcontroller and the non-volatile memory work correctly, this voltage is kept regulated.
  • converters with switched capacitors are also known, so-called switched capacitor converters, which invert an input voltage by recharging capacitors and / or multiply them in whole numbers.
  • switched capacitor converters which invert an input voltage by recharging capacitors and / or multiply them in whole numbers.
  • These types of converters likewise require a clock signal for the conversion, that is to say for the charge transport, and are therefore only to be regarded as a subset of the DC-DC converters.
  • the DC-DC converter is preferably operated at a third frequency in order to prevent interference with other activated transponders, for example during FSK transmission avoid or reduce.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

L'influence perturbatrice des impulsions d'horloge inévitablement émises par un convertisseur dans un système à transpondeur passif peut assurer une fonction utile si l'on utilise dans un convertisseur CC-CC des impulsions d'horloge commandées par un cristal de quartz au lieu du multivibrateur flou commandé par une horloge RC. Si l'on commande la fréquence du cristal de quartz à l'aide de diviseurs, on peut utiliser les impulsions d'horloge du convertisseur comme modulation FSK et transmettre ainsi des données du transpondeur ou de l'étiquette au lecteur.
PCT/EP1996/003646 1995-08-17 1996-08-19 Convertisseur cc-cc a modulateur fsk integre WO1997008811A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU68744/96A AU6874496A (en) 1995-08-17 1996-08-19 Dc-dc converter with integrated fsk modulator

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH2354/95-0 1995-08-17
CH235495 1995-08-17

Publications (2)

Publication Number Publication Date
WO1997008811A2 true WO1997008811A2 (fr) 1997-03-06
WO1997008811A3 WO1997008811A3 (fr) 1997-04-10

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1996/003646 WO1997008811A2 (fr) 1995-08-17 1996-08-19 Convertisseur cc-cc a modulateur fsk integre

Country Status (2)

Country Link
AU (1) AU6874496A (fr)
WO (1) WO1997008811A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001041057A1 (fr) * 1999-12-05 2001-06-07 Iq-Mobil Electronics Gmbh Systeme de transmission d'energie sans fil a tension de sortie elevee

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3760256A (en) * 1972-07-31 1973-09-18 Us Army Synchronous dc power supply
EP0281142A2 (fr) * 1987-03-06 1988-09-07 Omron Tateisi Electronics Co. Système d'identification d'objets
EP0596124A1 (fr) * 1991-12-04 1994-05-11 Citizen Watch Co. Ltd. Support de donnees
WO1995000922A1 (fr) * 1993-06-24 1995-01-05 Westinghouse Electric Corporation Systeme et procede d'identification avec etiquette passive

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3760256A (en) * 1972-07-31 1973-09-18 Us Army Synchronous dc power supply
EP0281142A2 (fr) * 1987-03-06 1988-09-07 Omron Tateisi Electronics Co. Système d'identification d'objets
EP0596124A1 (fr) * 1991-12-04 1994-05-11 Citizen Watch Co. Ltd. Support de donnees
WO1995000922A1 (fr) * 1993-06-24 1995-01-05 Westinghouse Electric Corporation Systeme et procede d'identification avec etiquette passive

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001041057A1 (fr) * 1999-12-05 2001-06-07 Iq-Mobil Electronics Gmbh Systeme de transmission d'energie sans fil a tension de sortie elevee
US6664770B1 (en) 1999-12-05 2003-12-16 Iq- Mobil Gmbh Wireless power transmission system with increased output voltage

Also Published As

Publication number Publication date
WO1997008811A3 (fr) 1997-04-10
AU6874496A (en) 1997-03-19

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